Resistance change memories are known as a type of semiconductor memory device. Magnetoresistive random access memories (MRAM) are known as a type of resistance change memory. MRAMs are memory devices using magnetoresistive elements having a magnetoresistive effect as memory cells storing information. Writing methods of MRAMs include a spin-transfer torque writing method. The spin-transfer torque writing method has a property that a spin-transfer torque current necessary for magnetization switching reduces as the size of the magnetic substance reduces, and has an advantage in high integration, reduction in power consumption, and improvement in performance.